This project has been established to evaluate human retroviruses in the Caribbean basin, with a particular focus on HTLV-I and HTLV-III. The focus of this project is on the epidemiology of the viruses in Trinidad and in the region, as well as investigations of diseases associated with this infection. The studies to be performed include a case/control analysis of clinically affected adult T-cell leukemia/lymphoma patients using study instruments adapted from parallel studies being performed in Jamaica and elsewhere. A study of the risk factors for seropositivity among a cohort of previously ascertained residents of Trinidad is also planned. A prospective evaluation of a sexually active populations, primarily male homosexuals exposed to HTLV-I and -III, is also to be undertaken. A follow-back through a normal population survey in Barbados originally ascertained in 1972 is planned to evaluate health effects of long-term HTLV-I infection. Historical collections of the Caribbean Epidemiology Center collected for various purposes, as well as future surveys to be conducted as part of human retrovirus surveillance, are planned in numerous regions of the Caribbean basin. Thus, a comprehensive series of parallel and coordinated investigations of human retroviruses is planned to determine the risk factors for infection and the risk factors for the various outcomes of infection, including leukemia/lymphoma, neurologic dysfunciton, and immunodeficiency.